QUARTERLY CHRONICLE. 143 
that the bodies of these animals consist of three well-defined, 
distinct, component tissues :—1, of an epithelial layer, with 
small round cells; 2, of a strong muscular layer; 3, of an ob- 
vious connective tissue, with exceedingly strong intermediate 
substance, analogous to what in vertebrates is known as 
hyaline substance. (See ‘ Koll. und Sieb. Zeitschrift,’ Jan., 
1865.) 
On the Circulation of the Blood in the Spiders of the genus 
Lycosa. By Ev. Cuapariips. (‘Annales des Sc. Nat.,’ Nov., 
1864.)—The distinguished author of this interesting paper 
remarks, in the first imstance, that injection is not a satis- 
factory method in the investigation of the circulation of 
the spiders. He has endeavoured to secure young spiders 
when transparent, and submitted them to the microscope. 
Those of the species Lycosa saccata (Holm.) were found most 
favorable. The works of Blanchard and Newport, and also 
of Dugés, have come under the particular notice of M. 
Claparéde. The Lycos observed were taken immediately 
after hatching and before the moult, which takes place in 
the mother’s ovigerous sac. The heart, or dorsal vessel, is 
situate in the median line, semicircular in profile, and reni- 
form in transverse section. At different parts it presents 
lateral diverticula, arranged in pairs, of which there are three ; 
of these the posterior are the least developed. At the level 
of each pair of diverticula there is a pair of those orifices 
like button-holes first discovered by Strauss in insects, and 
since detected in most Arthropods. They are called by the 
author “ venous orifices.” At the moment of diastole the 
blood rushes into the heart by these orifices. There are no 
valves to these orifices in the young Lycose, their movement 
depending merely on the general muscular fibre of the heart. 
The blood escapes from the heart by the thoracic aorta, and 
by a tubular posterior or caudal aorta, whence it communi- 
cates with a wide lacuna, occupying the pygidium and the base 
of the spinners. The heart itself is situated in a lacuna called 
the pericardial lacuna, whence all the blood entering the heart 
is derived. The details of the circulation and structure of 
its vessels are entered into most fully by M. Claparéde, and 
the views of Blanchard contested. The circulation in 
Lycosa is stated to be essentially lacunar, and M. Claparéde 
affirms that the vascular networks and reticulations in various 
Arachnide figured by M. Blanchard in his recent work, 
‘Organisation du Reégne Animal,’ are quite erroneous, and 
have no existence at all. 
Dr. Leonard Landois continues his exhaustive researches 
on the anatomy of the Pediculi parasitic on man. In his last 
